Rockville Weather in December

The climate in Rockville during December can be summarized as cold and a little damp.

December is in the winter in Rockville and is typically the 3rd coldest month of the year. Daytime maximum temperatures average around a freezing 4°C (40°F), whilst at night -5°C (23°F) is normal.

On average December is the 5th driest month of the year in Rockville with around 88mm 3.5 inches of rain making it a a little damp time to visit. This rainfall is typically spread over 12 days, although this may vary considerably.

On the flip side this corresponds to an average of 4 hours of sunshine per day.

The data used in these monthly averages covers a period of over 100 years right up until last year. As such they are a valid prediction of what to expect for the weather in Rockville in December 2025.